Wireless communication devices are ubiquitous. Among the many wireless communication devices that are now in operation are wireless communication devices that operate in accordance with one or more of the 802.11 family of protocols, for example, wireless communication devices used in wireless local-area networks (LANs), wireless mesh networks and Wi-Fi applications.
In many applications involving multiple wireless communication devices, the signals generated by the multiple wireless communication devices can interfere with one another. This is particularly the case in applications, such as applications involving LANs, wireless mesh networks and/or Wi-Fi, in which the multiple wireless communications device are in relatively close proximity of one another, for example, within a building.
Communication in accordance with the 802.11 family of protocols typically takes place in one of two different bands of the electromagnetic spectrum, namely, bands surrounding 5 GHz and 2.4 GHz. The bands in turn are divided into several channels centered at center frequencies that are approximately 5 MHz apart, where each channel occupies a band of approximately plus or minus 11 MHz about the respective center frequency of the channel, and each channel has an overall bandwidth of approximately 44 MHz. As such, adjacent or neighboring channels overlap one another to some extent.
Wireless communication devices operating in accordance with the different families of protocols, such as 802.11 and 802.16, typically are capable of selecting a specific channel for operation and then adhere to that selected channel. Conventional wireless communication devices have the capability of detecting when other wireless communication devices are operating in the same channel, and of adjusting to account for interference that can occur due to the shared usage of the same channel (e.g., through the use of a random access contention mechanism such as RTS-CTS handshakes).
As noted above, the various channels available in accordance with the 802.11 family of protocols overlap with one another to a fair degree. For example, the 802.11(b) protocol employed in applications such as Wi-Fi applications has 11 channels defined in the standard. Each given channel overlaps in its spectral width not only with neighboring channels (e.g., channel 6 tends to overlap channels 5 and 7) but also with channels that are non-neighbors (e.g., channel 6 also tends to overlap each of channels 2-5 and 7-10, albeit it does not overlap at all channels 1 or 11).
Further, while conventional wireless communication devices are generally capable of adjusting for and overcoming the effects of interference that arise from sharing a given channel among multiple wireless communication devices, conventional wireless communication devices tend to have difficulty adjusting for and overcoming interference that arises when other wireless communication devices are operating in neighboring, overlapping channels. Indeed, in many such cases, conventional wireless communication devices are unable even to detect that other wireless communication devices are operating in neighboring, overlapping channels, notwithstanding the fact that the wireless communication devices are experiencing inhibited performance due to interference from those other wireless communication devices.
Given these problems, conventional arrangements of wireless communication devices typically are set to minimize the amount of interference that can occur when multiple wireless communication devices are communicating in different channels. For example, again with respect to applications involving the 802.11(b) protocol having 11 channels, if two access points at which wireless communication devices are located are positioned nearby one another, the wireless communication devices at those access points are assigned entirely (or substantially) nonoverlapping and noninterfering channels (e.g., channels 1 and 6 or 6 and 11).
However, while this solution reduces the amount of interference, this solution is not ideal insofar as it limits the effective overall bandwidth that is available for communication among different wireless communication devices. That is, by restricting wireless communication devices to nonoverlapping and noninterfering channels, one avoids any use of the neighboring or intermediate channels (e.g., channels 2-5 and 7-10) for the communication of any information. Given that the use of wireless communication devices in a variety of applications continues to increase, and given that the amount of information being communicated among wireless communication devices also continues to increase, the decision to limit communication among devices to nonoverlapping, noninterfering channels increasingly threatens to hamper the performance of, or to dampen the development of, wireless communication systems.
For at least these reasons, therefore, it would be advantageous if an improved method and/or system for wireless communications, and/or method of making or constructing such a system, could be developed in which the use of available electromagnetic spectrum for communications by such a system was enhanced and yet, at the same time, the operation of the system was not significantly compromised by interference among the devices.